


The Worlds Beneath the Waves

by DownToTheSea



Category: Sanctuary (TV)
Genre: Adventure, Alternate Universe - Science Fiction, Alternate Universe - Subnautica, F/M, Friends to Lovers, Horror, Hurt/Comfort, Sea Monsters, Survival, stranded on an alien planet
Language: English
Status: In-Progress
Published: 2019-02-17
Updated: 2019-09-30
Packaged: 2019-10-30 01:22:27
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 6,309
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/17819138
Author URL: https://archiveofourown.org/users/DownToTheSea/pseuds/DownToTheSea
Summary: While on a classified mission, Captain Helen Magnus's ship suffers catastrophic damage from an unknown source. Along with her best friend and science officer Nikola Tesla, she evacuates in a lifepod to the surface of an unexplored ocean world, where she may be able to uncover the dark truth behind her mission and find the surviving members of her crew. But in a hostile underwater environment teeming with extraordinary life forms, even survival might be impossible.





	1. Safe Shallows: Part I

**Notes for the Chapter:**

> I picked up Subnautica on sale a little while ago and absolutely fell in love, particularly with the world and creature design. I just couldn't resist writing a Teslen AU in this universe, so here we are, haha. A big thank you to the wonderful notmyyacht for the help/suggestions with the plot, and also for putting Subnautica fanart on my dash the day after I started playing it. XD <33

_ Commanding Officer’s Log - Aurora _ __  
_ Date: April 8, 2193 _ __  
_ Time: 21:07 _ __  
_ Captain Helen Magnus recording _ __  
_  
_ _ The Aurora has arrived without incident at the ocean world 4546B and settled into planetary orbit. My crew commenced scanning the surface three hours ago, recording all data as protocol dictates for planets with no prior human contact. Tomorrow, we will resume our primary mission and perform a gravitational slingshot towards the planned site for the new phasegate. _

 

_ Personal Log - Aurora [encrypted] _ __  
_ Date: April 8, 2193 _ __  
_ Time: 23:54 _ _  
_ _ Captain Helen Magnus recording_

_ Nikola knows there’s something going on with this mission besides simply building a new phasegate out here. I knew he would figure it out. [Non-verbal audio detected. Text description: sigh.] Thankfully, he’s kept his theories to himself – so far. Knowing him, he’ll pick the most dramatic and least convenient time to blurt it out in front of everyone. The rest of the crew thinks the scans are routine fact-finding, for purposes of establishing a base here at a later time, but… I expect it will only be another day or two before he puts the rest of the pieces together. He will be  _ utterly  _ insufferable. _

_ I admit it may be a relief. A message came in from the Alterra board yesterday that rather troubled me, and I would very much like to discuss it with someone who’s amenable to hacking into the Alterra network. Then I could see what they’re really up to. But I suppose it will be a moot point if the scans come back negative. I’ll know tomorrow. _

 

Alarms were blaring. The afterimage of the Aurora igniting was seared into Helen’s eyes – she barely noticed the red lights flashing in the lifepod. It shook wildly as it rattled through the atmosphere, sparks flying from the consoles. Something ignited on the floor and fire sprang up on the other side of the pod. Helen gritted her teeth, but she couldn’t do anything about it right now; the impact would be coming soon.

When they did strike the water’s surface, it was with a massive jarring force that made her feel as if she’d been bounced right out of her body and then back in. Then they swooped up, the movement somewhat more measured, but still rough. Her stomach turned over.

The alarms and main lights went off on impact; they had lost power. The compartment was now bathed in the glow of emergency lights and the fire, which had turned from a flicker into a roar and was now taking up half the lifepod. She shot a worried glance at Nikola, strapped down in the seat opposite hers, but the fire hadn’t reached him yet. He wasn’t moving, and his head lolled against his chest. He must have been injured in the crash or the evacuation from the Aurora. She couldn’t tell if he was conscious or not, or – she refused to allow herself to think about the worst case scenario.

Her ears were ringing, but she was beginning to hear the roar and crackle of the fire as it crept toward them. She pressed a few buttons on her chair console to release her crash webbing, then swore when nothing happened. She slammed her fist into the panel. It finally retracted and she stumbled up, heading for the fire extinguisher she’d seen tossed onto the floor by the impact.

She snatched it up and aimed at the fire, not letting the stream up until she was certain the fire was out completely. She hadn’t realized how  _ loud  _ it was until it was gone. There was no sound in the lifepod now except the soft beeping of the emergency systems and her own breathing. Her heart was pounding, and she forced herself to slow it down.

“Hot,” Nikola mumbled from his corner of the lifepod. “Literally.”

Helen spun around to see him struggling to extract himself from his own chair. Relief lanced through her, almost stronger than she could bear for a second, before it settled into annoyance. (As it usually did with Nikola, her lifelong best friend and simultaneously the biggest pain in the ass she had ever known.)

“Don’t move,” she ordered as he finally freed himself. “You don't look very good.”

“I'm insulted.” Nikola was wobbling slightly and apparently decided it was wiser to follow her advice. He sat back down and groaned.

Wincing at the sparks continuing to fly from the power systems, Helen turned toward the medical kit fabricator and pulled a fresh one out. She went back to Nikola and knelt next to him, pushing back some of his ridiculous hair so she could see the gash on his scalp. He continued groaning while she applied a disinfecting salve, though she could tell he was playing it up.

“Doctor, captain, is there anything you can’t do?” he asked while she stuck plaster over the wound. A flirtatious eyebrow wiggle was interrupted by a wince when she probed the bump on his head and ran a medical scanner over him.

“Get you to be quiet, apparently.” Helen frowned at the scanner. It was telling her that minor head trauma was an optimal outcome considering their situation. Why Nikola built these things with such an attitude, she would never know. Rolling her eyes, she shut it down. “You’ll be fine, but you should probably take it easy for a day or two.”

“Yeah that seems really probable, since we just, you know, crashed on an entirely unknown planet.” Nikola’s hands waved in spirals, encompassing their surroundings.

“On that topic…” Helen helped him up with a glance at the sunlight shining through the overhead hatch. “Shall we see where we’ve ended up?”

They ascended the ladder, Helen in the lead with Nikola making grumbly noises behind her. She put a hand on the hatch and pushed hard. With a whoosh, it popped open and allowed a sharp breeze to flow past her, the tang of salt almost overpowering after the stale recycled air in the lifepod.

Helen pulled herself over the edge, watching a flat, manta-ray shaped bird that had come to roost on the pod flapping away with a squawk. Then she scanned the horizon, and froze.

“Helen, not that I’m complaining about the view, but do you mind?” Nikola’s voice floated up from beneath her.

Wordlessly, she cleared the exit and offered Nikola a hand up. He popped up from the hatch, his eyes going wide when he saw what she had.

They had landed in an endless ocean; there was nothing but water in any direction, no matter which way they looked. Nothing except for the remains of the Aurora, half-buried in the ocean before them and reduced to a smoldering ruin.

Nikola pulled out his own scanner. “Zero life signs,” he said. He turned in a smooth circle, scanning the entire area before meeting Helen’s eyes. “We’re the only living humans within scanning range.”

Helen swallowed. All of the crew should have made it into lifepods. Either they had landed too far away from them for Nikola to pick up, or…

Or she had led them all to their deaths on a mission they hadn’t even known about.

She turned away from Nikola, back to the wreck of the Aurora. It had to be nearly a mile away or more, but even from this distance she almost imagined she could smell it burning.

“Helen, don’t go all brooding commander on me,” Nikola said. He came up next to her, adding in a very low voice, “You couldn’t have known what would happen.”

No, she couldn’t have. And they would have been in orbit around this planet even if she hadn’t been tasked with a classified secondary mission. Yet still, she wished she would have been just a little more honest with her crew.

There was silence for a minute. Above the water’s surface it was utterly quiet, except for the sound of the waves and the distant rumble of the Aurora on fire. From orbit, she had seen the ocean covering the entire planet, and now that they were here on the surface, it was becoming clear just how vast it really was.

Vast enough that it seemed likely that at least some lifepods had survived the crash much as theirs had. For now, at least, Helen wouldn’t give up hope.

“What  _ did  _ happen?” she said at last. “Whatever it was put us into instant catastrophic failure and I barely got a look at the readings before starting the evacuation.”

“Some kind of massive energy pulse from the surface. I didn’t have time to do a more detailed analysis since  _ someone  _ yelled that I was a bloody idiot and yanked me away to a lifepod.”

“And I’d say that person deserves a little gratitude,” Helen pointed out. “That’s unfortunate, though. I thought perhaps you had gotten more.”

He shook his head.

“Look around us, Nikola,” she said quietly. “There were no signs of sentient life or advanced technology on this planet when we scanned it earlier. What could have hit us, and where did it come from?”

But neither of them had any answers.

 

After staring at the Aurora for a little while longer, they clambered back down into the lifepod and took stock of their situation.

“We need to get main power fixed first,” Helen said, eyeing the sparking systems uneasily. “And find a source of food and drinking water. We have the scanners, so we should be able to find sustenance that won’t kill us.”

“I adore your optimism.” Nikola had his head stuck in the storage container. “Got a little food and water here. A couple of protein bars, and… a pack of peanuts? You’d think this thing would be better stocked. Plus the fire extinguisher, in case we have any burning need for that while we’re stranded on an ocean planet.”

“If I’m letting you loose on my electrical systems, I think I’ll keep the fire extinguisher handy.”

Nikola ignored this. “As for drinking water, that shouldn’t be an issue. We have a limitless supply of salt water and a working standard fabricator. It won’t be hard for me to rig up a filtration system.”

Catching Helen’s look, he continued with a roll of his eyes. “Oh right, the survival blueprint database says otherwise. What is it we’re supposed to feed into the fabricator to get filtered water? A sparkplug, some wine, and the answer to life, the universe, and everything?”

“Don’t be ridiculous. A fish with an air bladder or, well, salt and coral,” Helen said stiffly, realizing that it  _ did  _ sound rather ridiculous when she put it like that.

“Edison,” Nikola muttered darkly. “I knew it was a mistake for Alterra to hire him for – ”

“Yes, very well,” she interrupted. “Just get us drinking water. What do you need to repair the power?”

Nikola eyed his scanner. “Mmm. Some titanium, some rubber, and some sulfur.”

“Sulfur?  Why on earth – ”

“It’s  _ science, _ Helen! Don’t question the science.”

She let out an exasperated sigh. “Hypocrite,” she muttered, before kneeling down to the hatch in the bottom of the lifepod.

Nikola straightened from his examination of the storage locker’s contents. “What are you doing?”

“Going outside to find what we need.” She lifted the lid of the hatch, peering below. The water was beautifully clear, sand visible not very far below, and a few fish swam into her line of sight before heading out of view. She was grateful that they seemed to have landed in the shallows.

“Well, then, I’m coming with you,” he said, dropping the storage compartment lid down with a clang.

“No, you’re not. I may have to go quite far or deep, and you’re hurt. You’re a risk to both of us if something goes wrong. And you need rest.” She took a water sample and scanned it, which informed her that it was filled with alien lifeforms but unlikely to kill her simply by touching it. She nodded, satisfied.

“I feel  _ fine, _ ” Nikola began, but she looked over and held up a hand.

“This isn’t up for debate, Nikola. You’re spending at least a day out of the water and that’s that.”

He actually pouted at her, but subsided as she swung her legs over the edge and into the water. “Scan everything that looks cool unless you think it’ll eat you.”

Helen smiled slightly at him. “If you have time, take a look at the radio before I get back. We’ll need to get a distress signal going.”

“Yeah.” Nikola’s hands twisted together before he stuck them onto his hips restlessly.

She thought he might have been about to say something else, but before he could speak she let go of the hatch edge and plunged down, her helmet sealing over her head as soon as she hit the water.

Her first impression was that she had been engulfed in startlingly clear, deep blue. It was everywhere she turned, and seemed to go on forever. Sunlight played throughout the water, filtering in beams down to the rolling sand below. Unfamiliar noises echoed eerily through the ocean, distorted to her ears: cries and clicks and the occasional distant bellow of underwater life calling to each other. For now, anything large seemed to be at a safe distance.

Once her eyes adjusted to the water, she could see an abundance of other colors further down: bright patches of darker blue and purple plant life with glowing cores and fronds of pale pink or green, reddish coral growing out from the rocks, and patches of greenish-brown seaweed waving here and there, though it was short and looked a great deal like grass.

Fish were swimming about her now, some getting closer to her curiously, but most darting away in fright. She spotted one frilly lavender fish that looked as though it might contain an air bladder, and filed that away to rub Nikola’s face in later.

Diving down, she swam far enough away to clear the lifepod before surfacing and orienting herself. The Aurora burned in the distance, but she estimated that she had at least half a mile before she would be exposed to any radiation. The shallows seemed to extend towards the ship, dropping off in every other direction, and for now Helen would prefer to stay in their relative safety unless she had no other option. So she kicked off towards the Aurora, diving underneath the surface again.

Titanium proved the easiest of Nikola’s list to procure. The ship’s hull was covered with it, and the crash had sent pieces scattering far and wide into the ocean. It was perhaps two minutes before Helen spotted a large chunk and, grunting, hauled it back to the lifepod.

“There’s plenty where that came from,” she told him as they heaved it inside, dripping water everywhere.

While swimming, she also managed to catch a few fish that made the mistake of getting too close or not being fast enough. She stuffed them in her pack to take back later; perhaps it would be enough for a meal and they could save the unperishable protein bars for later. One was a small, glowing orange fish that seemed to be 90% eye, which her scanner inexplicably told her would make a good meal. She looked at it dubiously, but kept it all the same.

There was an astonishing amount of variety in the underwater world they had crash-landed in. Perhaps a quarter of the way to the Aurora, the shallows dropped off temporarily into a deep mass of waving green kelp. Helen hovered near the edge for a moment, frowning as she looked down.

Her scanner was telling her there was something they could use to fabricate rubber down there, but the kelp was too thick to get accurate environmental readings. She didn’t like the idea of going headfirst into that forest without knowing what might be awaiting her, but with no rubber, there would be no power, and with no power, they were as good as dead anyway. Shaking her head, Helen rose to the surface to refill her lungs and allow some oxygen to seep back into her helmet before she took a long, deep breath, sealed it, and dived straight down.

Long, waving fronds would have tickled her as she passed through them if she hadn’t been wearing her environmental suit. As she went, she mentally noted that they needed to find a way to fabricate a thicker dive suit and an actual oxygen tank. She had an uneasy feeling they would need to go much deeper than these shallows to find everything they would need.

A warm orange glow appeared between the dark green foliage and Helen’s scanner beeped. Whatever was the source of that glow, it was also the potential source of rubber. She swam towards it, pulling out her survival knife.

The glow turned out to be from some kind of pods that were attached to the kelp plants, or  _ creepvine,  _ as her scanner informed her. Helen made another private note to tell Nikola to stop programming the scanners to give everything disturbing and/or dramatic names.

It didn’t take long to saw a few pods off and stick them in her pack. She was beginning to run low on air, but she considered the vines a moment longer. They needed materials for better suits, and the vines might provide the fibers they needed. Shrugging, she cut off a few samples of those as well.

She had stowed them in her pack and was just preparing to rise to the surface when she felt movement in the water behind her: something moving fast against the gentle current. A second later there was another push, accompanied by a swish of water being shifted directly behind her.

Helen wasn’t foolish enough to waste time turning around. She kicked up hard, angling for the surface and the shallows. Behind her, a harsh roar cut through the water. It was joined by more roars, from her left and right and below her in the depths of the kelp forest. Together they combined in a angry shriek that pierced through her suit and made her blood go cold.

She risked a glance behind her and wished she hadn’t. A shark-like creature with an impossibly long mouth covered in huge, jagged teeth was surging after her, bellowing again as she met its grayish-yellow eyes. From the sounds echoing through the water, there were at least three or four more joining the chase as well. That mouth was narrow, but it looked as if it could snap her in half without a second thought.

Heart hammering in her ears, Helen turned and threw everything she had into outstripping the shark to the safety of the shallows. Perhaps she had encroached on its territory, and it would let her be once she was out of their home.

With every passing second she expected to feel the creature’s teeth in her leg, but somehow she made it out of the forest and back to the shallows. She broke the surface and sucked in a breath but kept swimming, her arms and legs aching.

The roars subsided behind her, and her heart began to slow. She went a little further – the lifepod was close now, perhaps only twenty-five meters away – before she dared to stop and look behind her again.

She choked. The thing was  _ still right behind her,  _ swimming more silently than she ever could have imagined and joined by three of its companions, all closing in on her fast. The one in the lead was already opening its gaping mouth, and let out a scream that nearly deafened her at this distance.

Splashing wildly in her attempt to turn as quickly as she could, Helen darted away from it just as its jaws snapped shut on the space she had been. Now it was an all-out sprint to the lifepod, the sharks giving up on stealth and roaring after her as they pursued, their fins churning the water behind her, as she pushed her protesting body to its limit.

Even if she made it to the lifepod, she knew she wouldn’t have time to open the underwater hatch and climb in before they caught up to her. She would have to try for the ladder on the side.

The lifepod loomed up before her and Helen threw one hand and then another up onto the ladder, pulling herself up halfway. One shark lunged out of the water and she swung aside, its teeth snapping on empty air before it fell back in.

Her hands were shaking and she could barely grasp the rungs, but she made it up another few steps before the lifepod rocked back and forth. Another shark had thrown itself against the side. Her fingers slipped as the impact jolted her – for a moment she clung one-handed to the side of the pod, fighting both gravity and a wave of paralyzing fear as she dangled above the sharks, just barely keeping out of reach. Then with an effort she forced herself to move, grabbing the next rung and then the next, until she was kneeling on top of the lifepod.

It still shuddered under the concentrated attacks, but she was able to get the top hatch open and drop inside.

“Helen!” Nikola was standing in the middle of the pod with a worried frown, but his eyes widened and he caught her arm when she stumbled from another impact. She could still hear the creatures screaming outside, but now that she was safely sealed in the lifepod, it seemed to be coming from a long way away.

She sank to the floor, flinching away from the clear hatch window as one of the sharks flitted past. No matter how much air she gasped in, she couldn’t seem to get a full breath.

The lifepod was reinforced, she reminded herself. The sharks couldn’t break in, and they would go away eventually once they realized their prey was out of reach. They were safe.

“I… I have… kelp samples in my pack,” she managed. “And fish. You’ll… want to get them into storage as soon – ”

“I think storage can wait.” Nikola’s voice cracked and he dropped to his knees beside her. “Are you alright?”

“I’m fine. And if you won’t… bother preserving the damn things that I nearly died for, then I will.” Her words came out louder and sharper than she had intended, and she staggered to her feet, ignoring the concern in Nikola’s eyes.

The lifepod was still rocking, but the blows were coming farther and farther apart now. She yanked the fish and kelp out of her pack and dropped them into the cold storage section of the container before the pack slipped out of her trembling fingers.

“Bloody hell,” she breathed, and slipped to her knees again, suddenly exhausted.

Nikola was next to her in an instant. “Alright, what’s going on? Did you get stung by some kind of poisonous creature? Do I need to kill one of those sharks outside for the antidote? I could, ah, I could bean one in the head with the fire extinguisher. See, you were right, it might come in handy after all – ”

He was rambling, with the tiny knowing half-smirk that told her he was only doing it to disarm her, to get her to open up to him, or to cheer her up, but there was an undercurrent of real fear in his voice. When he tentatively reached out and touched her arm, Helen felt a little of the tension leave her body.

“I haven’t been poisoned, Nikola.” She leaned against the storage compartment, trying to regulate her breathing. “I’m only… a little shaken, that’s all.”

“A little,” Nikola repeated, but sat close next to her, letting their shoulders rub. “Well, I can see how being besieged by teeth monsters of death would do that.”

“Teeth monsters of death? Is that the best you can come up with?” Helen smiled a little despite herself.

Nikola took the scanner from her pack and checked the screen. “Stalkers,” he read.

Helen shuddered. It seemed all too apt a name considering how those creatures had followed her soundlessly, and so far beyond their own territory.

“Or teeth monsters of death!” Nikola said hastily, noticing her look. “Let’s go with that.”

“That’s not any better, Nikola.” But she was smiling again, even if it was rather unsteady.

“You’ve had a rough day, so I’ll forgive you for not recognizing my obvious genius.” Nikola got up and headed for the medical kit fabricator. Another roar sounded from below the pod, and he reeled back.

“I believe we would be well-advised to stay out of sight for a while.” Helen beckoned him over, taking his hand and pulling him down next to her.

She didn’t let go of his hand, not even when she drifted off into a shallow, restless doze. The whirr of the fabricator woke her up some time later; her suit was dry now, but she still shivered with cold.

The fabricator shut off and a soft, warm blanket was wrapped around her shoulders. Nikola sat down next to her once more, sliding his hand back into hers.

“You should have saved that for the environmental suits,” she murmured, but wriggled deeper into the blanket with a sigh.

“Fire me.”

“I just may. Are the sharks gone?”

“I think so,” he said in a low voice, squeezing her hand almost reflexively. “But it’s getting dark and I’d rather not stick any part of my deliciously appetizing self outside the hatch to check.”

“We’ll have to hope for the best tomorrow, then.”

“Yes. Or keep our trusty fire extinguisher handy.”

Helen’s laugh reverberated softly through the compartment.

 

Outside, night began to fall on Planet 4546B, its two moons rising smoothly over the rippling ocean surface. Several hours after Nikola thought they had left, a disappointed frenzy of Stalkers finally abandoned their latest prey, snapping up a few fish on their way home to make up for the loss.

It wasn’t worth wasting any more time here. Perhaps this prey would return to the kelp forest. Or perhaps not.

After all, humans never lasted long in these waters.

**Notes for the Chapter:**

> I am taking a few liberties with some game mechanics such as the storage system, scanner and fabricator functionality, etc. to improve the flow of the story. (I didn't figure anyone wanted to read ten pages of Helen and Nikola swimming around catching bladderfish or frantically googling where to find cave sulfur, haha. Not that I've done either of those things, of course...) And for anyone familiar with the Subnautica plot, there are some surprises in store! XD Anyway, I'm excited to keep going with this story and I hope you enjoy it! :D
> 
> Finally, I PROMISE to work on Charybdis and/or the Enchanted AU updates this weekend! I know I'm shamefully behind on those but I needed to get the first chapter of this out of my system first. XD I am eternally grateful for the patience <3


	2. Safe Shallows: Part II

**Notes for the Chapter:**

> An update? From ME? It's more likely than you think. (My sincere apologies for the delay!)

_ Personal Log - Degasi _ __  
_ Date: October 17, 2184 _ __  
_ Time: 16:38 _ _  
_ _ Ashley Magnus recording_

_ Got off my shift at 16:00 but had to spend forever reassuring my mom that the ship is in good shape and the captain isn’t going to murder us all in our sleep or something. She’s paranoid about this detour thing. I told her it was just to shave some time off our trip, but she wasn’t having any of it. Come on! I’ve only been working for these people for a couple months, does she expect me to demand they only take Mom-Approved Safe Routes? _

 

In the morning, Helen couldn’t even pretend she had slept well. Her head still hurt, her entire body ached, and her dreams were filled with lingering images of fire and long, sharp teeth. As dire as their situation was, it was almost a relief to open her eyes to reality again. When she did, she found her cheek pressed against Nikola’s shoulder and his hand still wrapped in hers. She  _ should  _ have wished he was safe, on some other ship or planet. But, selfishly, she was so, so glad he was here instead. She wouldn’t have wanted to be stranded alone in this place.

It was warmer now, as the backup systems of the lifepod absorbed the sun’s rays and turned them into heat and energy for the interior. The medical kit fabricator dinged as another one was automatically prepared using the solar power. Pushing the blanket off her shoulders, Helen sat up.

“Hrwghsn,” Nikola mumbled, jerking awake a moment later. He blinked at her dazedly. “Damn, I was really hoping I’d dreamed the whole thing.”

“No such luck, I’m afraid.”

Breakfast consisted of desalinated and filtered-to-hell-and-back ocean water, and a bit of fish roasted in their fabricator. (Not the eye-fish. Helen wasn’t quite desperate enough to try that one yet.)

Nikola had managed to patch up main power enough yesterday where it was no longer throwing sparks everywhere, which was the good news. The bad news was he still insisted he needed sulfur before he could fix it completely.

“Where in the world are we going to find that?” she asked at last, exasperated.

Nikola pointed down. “Right below us. I did some scanning yesterday – ”

“I thought I told you not to get in the water,” she said with a dangerous look.

“I didn’t! You didn’t say anything about sticking my scanner out of the hatch, though.”

Helen begrudgingly conceded this, and he continued.

“There’s a whole network of caves below us. There’s traces of sulfur there. Not a lot, but I don’t need that much.”

“Cave diving?” Helen said dubiously. It was far too easy to envision them both drowning before they could find Nikola’s precious sulfur. “Exactly how far down are these caves?”

“Ah!” Nikola gestured to the small unused heap of titanium he had shoved into a corner of the lifepod. “Never fear. I can whip a couple of oxygen tanks right up. Then we’re set. Easy as pie.”

Helen still wasn’t entirely convinced, but she didn’t see a better option.

It  _ was  _ a relief to have a proper oxygen supply attached to her suit. Nikola insisted on coming with her today, refusing to let the technicality that it hadn’t been a  _ full  _ day since they crashed stand in his way. Helen gave in eventually, but only after making him promise to stay close to her and get back to the lifepod immediately if he started feeling ill.

At last both of them were ready. Helen went first, battling her lingering reservations about the Stalker sharks coming back. But they had to get back in the water at some point, so she supposed it was best to have done with it. She opened the hatch and swung her legs out into the water, swallowing, and then dropped in.

Thankfully, there were no sharks anywhere near. Her scanner confirmed the evidence of her own eyes as Nikola slid into the water and shut the hatch behind him. He glanced around.

“Colorful.” His voice came through the suits’ comm systems, sounding clear if a little tinny. Then he gestured down, movements slow and drawn out in the water. “This way.”

There were rock formations all throughout this section of the ocean, most of them near the bottom, although a few curved up nearer the surface. Nikola swam down to the largest one within sight. Helen could see alcoves dotted across the stone, and at first she thought he was headed for those, but then he angled down, and she spotted a larger cave entrance at the foot of the underwater wall.

Nikola waited for her at the entrance, bobbing slightly as he held onto an outcropping stone to keep himself at this depth. “Captains first?”

Helen rolled her eyes – even if Nikola couldn’t see it through the suit, he would be able to tell – and accepted the flashlight he handed her. Then, she took a deep breath, clicked the flashlight on, and swam into the caves.

At first, it didn’t seem terribly different in here than outside. She could see the same coral types and plants scattered throughout the cavern, although the light they emitted was stronger here, with no sunlight to compete with. The passage she was in split off in two different directions, each tunnel just big enough for a person to fit through.

“You go right,” Helen said to Nikola, and took the left passage. The farther she got from the entrance, the darker it became. She was glad for the flashlight; without it, the only light was cast by luminescent blue and purple mushrooms scattered in irregular patches here and there. Out of the corner of her eye, she saw an outcropping of rock with distinctive veins lacing thick through it.

Helen grinned.  _ Copper.  _ Nikola would be thrilled. Quickly, she took out her survival knife, flipped it around, and knocked a fairly large chunk off the wall with the heavy-duty handle. She stowed it in her pack and continued moving along the cave floor. Her scanner informed her that the find had increased their probability of survival to  _ unlikely but plausible _ . Really, he had to start programming these things differently.

Still no sign of Nikola’s sulfur. Helen had just plucked a few mushrooms that scanned as having useful acidic properties when she heard the strangest noise echoing through the caves: a sort of hollow gurgling. It seemed to be quite a ways off, but coming from the passage Nikola had taken.

“Nikola?” she asked into the moment of silence that followed.

“Yeah, I heard it, I can’t figure out where it’s – ” Nikola’s voice was cuff off by another, louder noise: a growl, followed by a piercing whine.

She could hear Nikola swearing. The whine built up in intensity, drowning out his voice. Before Helen could make a move towards him or even say anything, it cut off into an explosion that rocked the cave walls.

“Nikola!” Helen called. The stone trembled around her before settling back into dead silence. She swam through the twisting cave as quickly as she could, branching off into the fork he had gone down. “Nikola!”

Her stomach turned over as she went round a corner. He was floating lifelessly in the passage in front of her, helmet scraping the cave ceiling as a faint current in the water pulled at his limp body.  _ Unconscious, _ she told herself, over and over again, while she cleared the last few meters towards him.  _ Just unconscious. _

“Nikola?” Her voice faltered slightly. She swept her flashlight around, but whatever had done this to him was long gone. Gently, she took his arm and spun him around to face her.

Her breath whooshed out of her in a massive sigh of relief; the readings on his suit showed her he was alive. He didn’t seem to be in great shape, though. His eyes opened as she was examining him, and he gave her a fuzzy look.

“Helen?”

“Don’t move,” Helen said, because she had just spotted something that made her go cold all over again. A crack in Nikola’s helmet, barely a scratch right now, but running the length of his face and liable to deepen or shatter at any moment. “Nikola, follow me, and slowly, alright?”

Nikola shook his head. “Not… Not without…” He gestured with his scanner, still clutched in his hand, and Helen belatedly saw a bulbous, dark red sac nearby, with a rough yellow powdery substance protected inside its folds. “Sulfur,” he told her with a smug, if not entirely all-there, grin.

Sighing, Helen quickly swam over and scooped up a couple of samples worth. “Happy? Now get moving. We need to get to the surface quickly.”

She held her breath all the way back, as if the smallest exhale on her part would shatter the reinforced glass protecting Nikola. She expected it to break at any moment. (Her scanner told her that her heart rate was elevated, which she ignored.) Nikola insisted it would hold, but she swam near him just in case.

Luckily, this time he was correct. Helen hung back and watched as he clambered slowly up through the lifepod’s bottom hatch, heaving himself over and lying on the floor with worrying lethargy. She pulled herself up after him, and sealed the hatch behind them.

“Let me look at you,” she said in a tone that brooked no arguments, before her helmet was even all the way off.

“Mmm, I love it when you get all captain-y,” he mumbled, but sat up and patiently allowed her to scan and prod him to her heart’s content.

“Well, by some miracle, you’re not seriously hurt,” Helen said at last, putting down her scanner and eyeing Nikola with no small amount of wonder. “But you’ve taken quite a beating in the last couple of days, and I don’t think you should exert yourself until you get a proper rest.”

Nikola threw his head back. “Ughhh.”

She glared at him. “I mean it, Nikola. For all intents and purposes we’re alone out here – ”

“Ooh, sexy.”

_ “Nikola.  _ We can’t afford to take risks. I need – your expertise.” She cleared her throat, her cheeks warming for no good reason. “Anyway, it’s best if you stay here to get all our systems up and running.”

He gave her a mocking bow. “As my captain wishes.”

Helen rolled her eyes, but a sarcastic Nikola was better than a sulky Nikola, or worse, a dead Nikola, so she let him struggle to his feet and make his way over to the power systems. For a while, she watched him work, occasionally causing something to spark or swearing under his breath.

“What attacked you in the caves?” she asked at last.

He looked up. “Not sure. Some kind of orange fishy-thing, came out of nowhere and just… blew up. Exactly what we needed, right? Exploding fish. Exploding fish that apparently  _ loathe  _ us.”

Helen grimaced. “We’ll have to be more careful. That whining sound must have been a threat of some sort. If either of us hears it again…”

“Get the hell away?”

She dipped her head in assent. “Couldn’t have put it better myself.” After a moment’s silence, she spoke again. “It makes me wonder, Nikola…”

“How our exploding fish friend could bear to try blowing holes in this pretty face?”

Her lips pursed in a tight smile. “No,  _ that  _ I can understand. I’m afraid I wasn’t thinking about your pretty face.”

“Disappointing, but go on.”

“If these are the sorts of creatures we’re encountering in the shallows… What’s further down?”


End file.
